Telephone  repeater system



v v 642,749 p 2 5 1927" A. F. ROSE TELEPHONE REPEATER SYSTEM Filed March24, 1921 dXXb avwmtoz 14.}? R056 Patented Sept. 20, 1927.

PATENT FFEQEO ARTHUR r. nosn, or wnsrnnierrron, NEW YORK, ASSIGNOR rAMERICAN TELE- PHONE AND TELEGRAPH coMranY, a c'onronnrro'n on NEW YORK.

TELEPHONE nnrnarnn SYSTEM..

App'iicationfiled March 24, 1921. Serial No. 455,296.

The principal object of my invention is to provide a new and improvedrepeater system adapted for operation between lines of differentcharacteristic impedance. Another objectof my invention is to provide arepeater witha single repeating element or series-of repeating elementsto operaterbe- I tween two lines, each balanced by a respectiveartificialline. These'objects and other objects of my invention willbecome apparent upon consideration of a specific embodiment of thel11V61ltlO11,,Wl1lCl1 I will now proceed todisclose, with theunderstanding that the invention is defined in the appended claims. Theaccompanying drawing is a diagram showing my improved repeater system,1n connection with a loaded line and a smooth line, by way of example.

' The transmission lines 11 and 13 between which it is desired torepeat, may be any two lines having the same characteristic impedance ordifferent characteristic inipedances. I have shown the line 11 as aloaded line with the loading coils 12 and with any convenienttermination which may be at part-section or at part-load. The line 13 isshown as a smooth lines The network 22 is designed accurately to balancethe line 11 and the network 22 provides a similar balance for the line13. The usual hybrid coil transformer14l-16 is provided between the line11 and the network 22. At the middle points 15 of the coils 14:, theconductors 17 carry the input to the repeater element 19. Similarly,from the hybrid coils associated with the line-13, the conductors 17bring the' input, both the conductors 17 and 17 being united at 18 tocarry the input currents to the element 19. g r

Theoutput currents from the repeater element '19 go through a wavefilter 20, whose function will be explained presently, whence thebranch'conductors 21 and21 go respectively to the coils '16 and 16 ininductive relation with the series coils 14L and 1%.

The useful frequency range may be less than the entire frequency rangebelow the 7 critical frequency for the loaded line 11, and it may bedesirable to make the network 22 balance the'line 11 over only theuseful frequency range. 'Accordingly, the lowpass wave filter 20 isprovided, having its critical frequency corresponding to the upper limitof the useful frequency range, so

that other frequencies shallnot be line'from the repeater element 19.

' Assuming that voice currents come in from the left over theline 11,they will flow in considerable proportion through the branch conductors17 and again in considerable proportion through the conductors 18 totheinput side of the repeater element 19. The amplified currents from therepeater element 19 will be restricted to the useful frequency range bythe wave filter 20. These output currents, after passing through thefilter 20, will divide to the branch conductors 21 and 21. The currentsin the conductors 21" and the coil 16 will induce cur rents in the coils1 1, the energy of which will divide equally to the line 13 and theartificial line 22.

Thus the current output from the filter 20 will be divided twice, sothat only a quarter of the energy-output from the filter 20 will be puton the line 13. However, it is easy to amplify to the necessary extent,and the repeater element 19 may comprise more than one amplifyingelement in tandem relation, if so desired.

On account of the location of the points 15 midway in the'divided coil14 and because of the balance between the artificial line 22 and theline 13, none of the output energy received through the branchconductors 21 and coil 16 will be put in the con ductors 17. This is animportant consideration because if any of the output energy passes tothe input, singing may result, with obvious impairment of the service.

Just as the output energy going over the conductors 21 is balanced outas to its effect on the input circuit v17, so the output through 21isbalanced in its effect on the input conductors 17 I claim:

1. In combination, two transmission lines, each balanced by a respectivenetwork, with a respective hybrid coil between each said line and itsnetwork, a single repeater element and input connections thereto fromboth said coils and output connections there- 'from to both said coils.

lation with a respective line independently put on the r of theremaining line and network, a common an'iplitying element, means tocarry the inputs from both lines to said element, and

means to divide the output therefrom toboth saidlines.

line independently of the remaining line and network, and a singlerepeater element with like input connections from both lines and a pairof output conductors, the said input conductors'being connected inmultiple and a 35 alike with the-two lines and the" s-aidontput likeoutput connections to both lines.

4-. In combination, two dissimilar lines, respectivenetworks balancingsaid lines, re-' spective hybrid coiltransformersbetween each line andits network-,a repeaterelementconnected on its input side alike withsaidtranstoriners' a wavefilterj connected to the.

' "output :sidefot; theflsaid' repeaterelen ientand ill!like-connections from said filter to said --tr-a'nsfor1r i'ers.

5. In combination, two transmission lines,

each balanced by a respectivenetwork, with 30 'a respectivehybrid'coilbetween each said line and its network, a single repeater. eleinenthaving a pair of inputoonductoif's, and,

conductors also being connectedin multiplefi and allkefwith saiduli'nes'and o thatwthe-out; In tcurrcnt's areot-"no'eflf i putcondiictors: ii Inte'st'i'n oiiyiw-he nanie to thisfspecil'ica on this 1; Ma1-'c11;,-1921.

